(a) Explain the term electrodes in electric cells.... | WAEC SSCE - Physics - 2012

Question 1 Report

(a) Explain the term electrodes in electric cells.

b) An electric current passing through an electrolyte for 2 minutes deposited 200 g of a substance. If the electrochemical equivalent of the substance is 8.33 x 10\(^{-4}\)g C\(^{-1}\), calculate the current passed.

Answer

(a) Electrodes in electric cells

Electrodes are the two conducting plates or rods through which electric current enters and leaves the electrolyte in a cell. The electrode by which conventional current enters the electrolyte is the anode (positive), and the one by which it leaves is the cathode (negative).

(b) Calculating the current

By Faraday's first law of electrolysis, the mass deposited is \( m = Z I t \), where Z is the electrochemical equivalent, I the current and t the time.

Given: \( m = 200\,\text{g} \), \( Z = 8.33 \times 10^{-4}\,\text{g C}^{-1} \), \( t = 2\,\text{min} = 120\,\text{s} \).

\[ I = \frac{m}{Z t} = \frac{200}{(8.33 \times 10^{-4}) \times 120} \]

\[ I = \frac{200}{0.09996} \approx 2.0 \times 10^{3}\,\text{A} \]

The current passed is about 2000 A.

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Answer Details

(a) Electrodes in electric cells

(b) Calculating the current

By Faraday's first law of electrolysis, the mass deposited is \( m = Z I t \), where Z is the electrochemical equivalent, I the current and t the time.

Given: \( m = 200\,\text{g} \), \( Z = 8.33 \times 10^{-4}\,\text{g C}^{-1} \), \( t = 2\,\text{min} = 120\,\text{s} \).

\[ I = \frac{m}{Z t} = \frac{200}{(8.33 \times 10^{-4}) \times 120} \]

\[ I = \frac{200}{0.09996} \approx 2.0 \times 10^{3}\,\text{A} \]

The current passed is about 2000 A.

Read lesson note on Current Electricity (JAMB)

Read lesson note on Electric Cells (JAMB)

Current Electricity

Electric Cells

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